Electrolysis of metallic solutions.



F. LAGROIX.

ELEGTROLYSIS OF METALLIC SOLUTIONS.

APPLICATION FILED FEB.19.1910.

Patented Mar. 12, 1912.

R O w m N I citizen of the Republic of France, residing zit-Paris, in theRepublic of France, have for many years ast, because the practical success of. such e ectrolysis seems to present the simplest solution of the treatment of -ores.-

.rn'arrann Lncaoxx, or rants, nan-Ken.

ELncrnoLYsIs or i METALLIC SOLUTIONS.

Specification of Letters Patent.

Patented Mar. 12, 1912.

Application flled'lebruary 19, 1910. Serial No. 544,875.

To all whom may concern Be it known that I, -FERNAND LAGRQIX, a

invented certain new and useful Improvements in or Relating to the Electrolysis of Metallic Solutions, of which the fol owing is a specification. Y

The direct electrolysis of more or less rich and ure metallic solutions derived from the iixiviation' of mineral ores, has been the subject of repeated experiments In the metallurgy-of copper, for instance, there arqat present employed two kinds of processes.- In the one known as the wetroces's, the ,ores are first subjected to a ixiviation preceded or otherwise byvarious 1 erations suchas-roas ting, exposure to air and so forth; and in the solutions thus obtained, the copper is precipitated in the condition of cement copper, the value of which is inferior to that of electrolytic copper.

This precipitation is obtained by means of iron scrap and for each ton of precipitated "copper, a consumption of iron rarely less nature of the ore,treated. The y than two tons must'must be allowed for. The other processes, so-called dry processes,

,consist in gradually concentrating the copper contained in theore by a series of operations, such as roasting and fusing, the number of these operations dependin on the.

roc-

ess yields as its final product ingots o raw co per. 'gvhether the copperbe obtained in the cement form or in the form of ingots, it must be subjected to a final refining, which is ordinarily an electrolytic prpcess, by means of-which the raw copper obtained is brought into-solution and deposited on a cathode in the condition of pure copper. This explanation makes it'ev'ident at once what-a great simplification would be intro duced in the metallurgy of copper by a roces'senabling chemically pure co per to directly obtained by the electroysis of cupreous solutions of any suitable kind, ob-

taincd by the lixivia'tion of the ore.

This invention relates to The processes accordin to the present invention consist in electrolyzing metallic solutions of any suitable percentage and compositlon between an insoluble anode, fixed or otherwise, and a suitable cathode, preferably metallic, having a sufiiciently rapid movement of displacement.

In order to fully understand the importance and thenovelty of the processes form ing the subject of the, present invention, it

will be useful to ascertain What takes place in the electrolysis of impure cupreous solu- When the method of electrolysis is applied to a low percentage cupreous solution, such as the solutions which are formed by the lixiviation ofthe o res, (andv which contain, for instance, 1% of. copper, 3.5% of iron, and 2% of sulfuric acid,etc.),

the sulfate of copper isdecomposed in the first place, and-the copper is deposited on the cathode while the radical S0 is transferred to the anode; but in poor and impure I rocesses enablmg this latter condition to e realized.

cupreoussolutions of this kind, the copper is no longer deposited in a coherent condition as soon as the intensity of the current exceeds 10-15 amperes per square meter of cathode. ,The radical SO, then meets at the anode ,the ferrous salts, and immediately converts them into ferric salts, which in their turn dissolve the copper deposited on the cathode in proportion 'a s itis deposited, especially if this deposit is powdery and not very coherent, and thereforethe result ofthe electrolysis IS ml under such conditions.

The yield of an apparatus composed, for instance, of lead or carbon anodes immersed opposite copper cathodes in a poor solution of copper is therefore absolutely prohibitive for practical purposes. It must also be pointed out that in such an apparatus theredifierences -of resistance which are local cause the deposit to be of differentcom ferent plates, so that local currents are caused to flow'between the parts of the *sition, appearance and quantity on the ifplates themselves; the effect of these currents is to cover certain plates at the expense of others, so that under these con ditions an abundant and spongy deposit produced on certain plates, and no deposit on others.

Eli'orts have been made to remedy thesolvent action of ferric salts by enveloping the anodes in diaphragr ns, the action of which is satisfactory at rst but after a time becomes unsatisfactory, without taking into account the fact that this diaphragm is not very suitable for industrial use and is rapidly destroyed. Effort-s have also been made since 1886, in Germany, since the appearance of the Marchcse process, to depolarize the insoluble anodes by means of sulfurous acids derived from the roasting of the ore. This process while excellent in principle has not been practically carried out.

N ow according to this invention the probis solved by taking into account the causes of failure which have just been mentiohed and applying thereto the following remedies.

The invention will be described in connection with the. accompanying drawings in whichz Figure 1 is a sectional elevation of the cell, and Fig. 2 is a sectional plan view of the same on the line A, A of Fig. 1.

The electrolyzer consists of an insoluble anode 0, preferably perforated, and arranged around a cathode 12 formed of a. metal cylinder to which a vigorous rotary movement is imparted. The electrolyte is ad mitted to the cathode compartment of the cell a by the inlet pipe d, passes through the holes-in the anode and overflows by means of the pipe 6. If the cathode employed has a surface of a square meter, for instance, the dimensions being 1 meter in length and 1 meter in circumference, and assuming that this cathode revolves at the rate of 40 revolutions per minute, there will be available for the cathodic deposit during one minute, a cathodic surface equal to 40 square meters; a current intensity can therefore be employed which is 40 times greater than that which can be utilized in an apparatus having fixed anodes and cathodes of 1 meter of surface, While moreover a good and compact deposit is obtained, because the surface of the cathode is constantly brought in contact with fresh molecules of sulfate of copper 01' of the metal treated. If however the surface is thus increased artificially to 40 times that of an apparatus with a fixed cathode, the action of the ferric salts will be practically the same and not certainly greater than before; hence, it in the fixed apparatus where the deposits are, for instance, 10 gr. per hour (movement of 10 amperes per square meter), the ferric salts will dissolve all the copper deposited, in'the esses employing fixed anodes and cathodes with depolarization by sulfurous acid, if must 'be noted that in such apparatus as has been hcreinbefore stated, local couples aris- J ing from differences in the resistance exist- Q ing between the anodes and cathodes produce irregularities in the deposit, such that 'on certain plates the copper is good while on the others it is spongy, and hence a. metal is obtained which can only be compared as regards qualitywith cement copper. In the rotary electrolyzer on the contrary everything is symmetrical and there are no local couples between the-various parts of the cathode; the deposits obtained are also absolutely regular and correct, even when employing current densities of 200 to 400 ampores per s uare meter of cathode, and-I impure solutions only con- 1- working wit taini-ng 1% of copper and less.

Further the construction of the electrolyzer is such that the solution entering the cathode compartment is brought by centrifugal force through the immediately j perforated anodes and escapes by an overinto a useful action, because the anode solu tion which is rich in ferric salts is senton to the roasted metal, in order to dissolve the 0, id and even the little sulfid of copper,

\ hich it may contain. From the lixiviation vats these copper solutions, enriched in consequence of t e action of the ferric salts, and the acids which they contain, on the metallic, oxids of the ore, return to the electrolyners directly iiFaftenhaving passedinto coke towers Where they encounter the sulfurous gas derived from the roasting of the ore. In this case the ferric solutions are completel reduced to ferroussolutions with the pro action of sulfuric acid, before entering the compartment. of the cathode where they can no longer have a deleterious action.

I declare that what Iclaim is An electrolytic cell for separating metals from their impure solutions, comprising a rotating cathode, a stationary concentric anode dividing the cell into two parts and nomeee 8 provided with a large number of small per- In Witness WhBIBOf,I havehereunt o signed forations through which the whole of the my name this 5th day of February 1910, in electrolyte passes and carries away the im tne presence of two subscribing wltnesses. 10

purities produced at the anode, an inlet pipe FERNAND LACROIX. 5 for admitting electrolyte to the space inside Witnesses the cathode and an outlet pipe for the same A 9 MEJEAN, outside the cathode. 1 T COKE. 

